The mechanism of mammalian polyamine transport is poorly understood. We have investigated the role of plasma-membrane potential (DeltaPsipm) in putrescine and spermidine uptake in ZR-75-1 human breast cancer cells. The rate of [3H]putrescine and [3H]spermidine uptake was inversely correlated to extracellular [K+] ([K+]o) and to DeltaPsipm, as determined by the accumulation of [3H]tetraphenylpho...

The activities of Na-K-ATPase and Na-K-2Cl cotransporter (NKCC1) were studied in the aorta, heart, and skeletal muscle of streptozotocin (STZ)-induced diabetic rats and control rats. In the aortic rings of STZ rats, the Na-K-ATPase-dependent (86)Rb/K uptake was reduced to 60.0 +/- 5.5% of the control value (P < 0.01). However, Na-K-ATPase activity in soleus skeletal muscle fibers of STZ rats an...

abstractin order to investigate the effects of the inoculation with p. putida, r. leguminosarum bv. phaseoli and f. mosseae on yield and nutrient uptake of common bean (phaseolus vulgaris l.), a greenhouse experiment in a completely randomized factorial design with 3 treatment including a: microorganism in four level (no inoculation, p. putida, f. mosseae and mix inoculation of fungi and bacter...

The choroid plexus uptake of [(3)H]cefadroxil was studied in peptide transporter 2 (PEPT2) wild-type and null mice as a function of temperature, transport inhibitors, pH, and saturability. At normal pH (7.4) and temperature (37 degrees C), the uptake of 1 microM cefadroxil was reduced by 83% in PEPT2(-/-) mice as compared with PEPT2(+/+) mice (p < 0.001). A further reduction was achieved in nul...

Several components of branchial copper uptake were identified in juvenile freshwater rainbow trout (Oncorhynchus mykiss) using (64)Cu. On the basis of competitive interactions between sodium and copper uptake, inhibition of copper uptake by a proton pump inhibitor (bafilomycin A1, 2 micromol l(-1)) and a Na(+) channel blocker (phenamil, 100 micromol l(-1)), it appears that a proportion of the b...

The cultivatioo of narrow·leafed lupins (Lupinus angustifolius L) increases rates of subsoil acidification, and this is thought to be partly related to their pattern of nutrient uptake and H+ jOHexcretion. The main hypothesis of this study was that H+ and OHexcretion is not distributed evenly over the entire length of the root system but is limited to zones where excess cation or anion uptake o...

17alpha-Ethinylestradiol (EE2), a component of oral contraceptives, is known to undergo considerable first-pass 3-O-sulfation in the intestine and liver. Once formed, the 3-O-sulfate conjugate (EE2-Sul) is detected in circulation at appreciable levels (versus parent EE2) and is present in bile. Therefore, hepatic uptake of EE2-Sul was assessed with suspensions of cryopreserved human primary hep...

We report the H2 uptake properties of six covalent organic frameworks (COFs) from first-principles-based grand canonical Monte-Carlo simulations. The predicted H2 adsorption isotherm is in excellent agreement with the only available experimental result (3.3 vs 3.4 wt % at 50 bar and 77 K for COF-5), also reported here, validating the predictions. We predict that COF-105 and COF-108 lead to a re...

Kinetics of nitrite uptake and reduction by Chlamydomonas reinhardtii cells growing phototrophically has been studied by means of progress curves and the Michaelis-Menten integrated equation. Both uptake and reduction processes exhibited hyperbolic saturation kinetics, the nitrite uptake system lacking a diffusion component. Nitrite uptake and reduction showed significant differences in K(s) fo...